How to deal with missing out on things?

Hello, so my mom and stepdad are getting married this weekend in a random town hours from home, which means I won't be able to attend it due to my agoraphobia. This along with other things I've been missing out on make me feel really sad and alone (as well as some guilt for being a "let down", even though I know that is an irrational feeling). My question to y'all is how you have dealt and coped with missing out on things? Thank you for your answers :)